Tire insert and vehicle wheel comprising said tire insert

Abstract

A tire insert for vehicle wheel which has an annular element made in one piece of polymer material is provided. The annular element has a base portion suitable for being accommodated in a rim seat of a rim and an enlarged portion having a section larger than the base portion. The enlarged portion is shaped to have shape and size to always be spaced apart from an inner tire side when the tire is inflated to a predetermined standard working pressure. When the tire is deflated, the enlarged portion comes into contact with the tire to support the tire while the vehicle wheel is running. A vehicle wheel having a tire, a rim onto which the tire is mounted, and the tire insert is also provided.

What is claimed is: 
     
       1. A tire insert for a vehicle wheel suitable for being inserted into an inner annular cavity resulting between a tire and a rim of the vehicle wheel, the tire insert comprising an annular element made in one piece of polymer material and suitable for coming at least partially into contact with the rim of the vehicle wheel, the annular element comprising a base portion suitable for being accommodated in a rim seat of the rim and an enlarged portion having a larger section than the base portion,
 wherein the enlarged portion comprises an outer enlarged portion surface of convex shape suitable for facing towards an inner tire side, 
 wherein the enlarged portion is shaped to have such shape and size that said enlarged portion always remains spaced apart from the inner tire side when the tire is inflated to a predetermined standard working pressure and such that, when the tire is deflated or when the tire is inflated to a pressure much lower than the predetermined standard working pressure, the enlarged portion comes into contact with the tire to support the tire during movement of the wheel, 
 wherein the tire insert is entirely made of ethylene vinyl acetate (EVA) having a density comprised between 0.08 and 0.12 g/cm 3 , a breaking load comprised between 10 and 14 kg/cm 2 , an elongation at break comprised between 200% and 300%, a tearing degree comprised between 1.5 and 2.5 kg/cm, a compression degree comprised between 50% and 70%, and a hardness either comprised between or equal to 16-21 Shore A, the hardness tending to change as ambient temperature changes. 
 
     
     
       2. The tire insert of  claim 1 , wherein the enlarged portion is shaped to have such shape and size that said enlarged portion always remains spaced apart from the inner tire side so that there is a space between the outer enlarged portion surface and the inner tire side, and so that said space has a decreasing course from an insert portion farthest from the rim to an insert portion closest to the rim when the tire is inflated to a predetermined standard working pressure. 
     
     
       3. The tire insert of  claim 1 , wherein the enlarged portion has a bowl-shaped section, with a convex top edge having convexity facing an inner side of the tire. 
     
     
       4. The tire insert of  claim 1 , wherein the base portion is neck-shaped and comprises a lower base suitable for resting against the rim and an upper base that is joined to the enlarged portion and is tapered with respect to the lower base, the upper base having a smaller section. 
     
     
       5. The tire insert of  claim 1 , wherein a total radial height of the tire insert is between 20 cm and 50 cm. 
     
     
       6. The tire insert of  claim 1 , wherein the tire insert is entirely made of an expanded polymeric material. 
     
     
       7. A vehicle wheel comprising:
 a tire and a rim onto which the tire is mounted, the tire comprising an inner tire side facing an opposite side of a tread of the tire; 
 a tire insert mounted in an inner annular cavity resulting between the tire and the rim of the vehicle wheel, the tire insert comprising 
 an annular element made in one piece of polymer material and suitable for coming at least partially into contact with the rim of the vehicle wheel, the annular element comprising a base portion suitable for being accommodated in a rim seat of the rim and an enlarged portion having a larger section than the base portion, 
 wherein the enlarged portion comprises an outer enlarged portion surface of convex shape suitable for facing towards an inner tire side, 
 wherein the enlarged portion is shaped to have such shape and size that said enlarged portion always remains spaced apart from the inner tire side when the tire is inflated to a predetermined standard working pressure and such that, when the tire is deflated or when the tire is inflated to a pressure much lower than the predetermined standard working pressure, the enlarged portion comes into contact with the tire to support the tire during movement of the wheel, 
 wherein the tire insert is entirely made of ethylene vinyl acetate (EVA) having a density comprised between 0.08 and 0.12 g/cm 3 , a breaking load comprised between 10 and 14 kg/cm 2 , an elongation at break comprised between 200% and 300%, a tearing degree comprised between 1.5 and 2.5 kg/cm, a compression degree comprised between 50% and 70%, and a hardness either comprised between or equal to 16-21 Shore A, the hardness tending to change as ambient temperature changes; 
 wherein the tire insert is mounted in the inner annular cavity resulting between the inner tire side and the rim, wherein the annular element is positioned so that the base portion is in contact with the rim in the rim seat, and 
 wherein the tire insert is shaped and sized so as not to entirely occupy a volume of the inner annular cavity; 
 the enlarged portion being shaped to have such shape and size that said enlarged portion is spaced apart from the inner tire side when the tire is inflated to the predetermined standard working pressure, and when the tire is deflated or when the tire is inflated to a pressure much lower than the predetermined working pressure, the enlarged portion is in contact with the tire to support the tire during movement of the vehicle wheel and to prevent tire sidewalls from wearing out. 
 
     
     
       8. The vehicle wheel of  claim 7 , wherein between the outer enlarged portion surface and the inner tire side there is a space having a decreasing course from an insert portion farthest from the rim to an insert portion closest to the rim when the tire is inflated to the predetermined standard working pressure. 
     
     
       9. The vehicle wheel of  claim 7 , wherein the base portion is neck-shaped and comprises a lower base suitable for resting against the rim and an upper base that is joined to the enlarged portion, and wherein also the base portion always remains spaced apart from the inner tire side when the tire is inflated to the predetermined standard working pressure. 
     
     
       10. The vehicle wheel of  claim 7 , wherein an inner diameter of the tire insert, when the tire insert is not mounted to the rim, has a shorter length than an inner rim diameter, such that when the tire insert is mounted to the rim the tire insert applies a radial pressure to the rim seat to stabilize adhesion to the rim.